A fluid ejection device, such as an ink jet printhead, may comprise a substantially linear column of firing chambers with firing resistors. The firing resistors typically have associated drive circuits with drive transistors which energize the resistors to expel fluid from the chamber through an orifice or nozzle. The drive transistors are arranged in a column along side of and substantially parallel with the column of firing resistors. Although a vertical column of resistors is substantially linear, some resistors may be offset horizontally as disclosed, for example, in U.S. Pat. No. 5,635,968.
The fabrication of a fluid ejection device may include a surface etch using an etchant such as TMAH. The etch takes place after the transistors have been fabricated on the substrate. The transistors include contacts which provide an electrical contact to the substrate through vias in an insulation layer. During a subsequent etch, the etchant attacks, i.e. etches away additional portions, of the substrate through openings in the insulation layer through which the contacts pass. The attack often occurs through pinholes located in a passivation layer above the insulation layer in the region of the contacts.